Tella Lantta,1 Raija Kontio,1–3 Michael Daffern,4 Clive E Adams,5 Maritta Välimäki1,6,7 1Department of Nursing Science, University of Turku, Turku, Finland; 2Helsinki University, Helsinki, Finland; 3Helsinki University Hospital, Hospital District of Helsinki and Uusimaa, Helsinki, Finland; 4Centre for Forensic Behavioural Science (CFBS), Swinburne University of Technology, Melbourne, VIC, Australia; 5Institute of Mental Health, University of Nottingham, Nottingham, UK; 6Turku University Hospital, Turku, Finland; 7School of Nursing, The Hong Kong Polytechnic University, Hong Kong Purpose: This paper aims to explore the acceptability of Dynamic Appraisal of Situational Aggression (DASA) from the perspective of patients, its actual use by mental health nurses, and the predictive validity of the DASA instrument. Methods: A feasibility study design incorporating quantitative and qualitative components was used. The study was conducted in three mental health inpatient units at three hospitals in southern Finland. Quantitative data were used to explore demand (nurses’ actual use of the DASA), limited efficacy (predictive validity), and acceptability (measured through patients’ participation in the project). Qualitative data were collected to enhance the understanding of acceptability by describing patients’ perceptions of the strengths and weaknesses of the DASA. Results: Nurses used the DASA for most patient assessments. The predictive validity of the DASA was outstanding or excellent, depending on the type of aggression predicted, although the patient recruitment ratio was low. Patients reported both strengths and weaknesses of the DASA, providing complementary information regarding the instrument’s acceptability and clinical application. Conclusion: The DASA accurately predicts inpatient aggression. The patients’ preferences and concerns regarding risk assessment have been noted. More patient involvement in risk assessment research and violence prevention efforts is required. Keywords: patient participation, nurses, violence, risk assessment, psychiatric hospitals, multi-method approach